Photocarcinogenesis: lack of enhancement by fluorescent white agents

These studies were designed to determine whether fluorescent whitening agents (FWAs) could: (I) produce an augmented acute response of skin to a single ultraviolet light exposure (i.e., phototoxicity), or (II) increase the number or hasten the appearance of skin tumors after several ultraviolet light exposures (i.e., chemically enhanced photocarcinogenesis). Five substituted stilbene FWAs were screened for phototoxicity. The results of pretreatment with these agents were compared with pretreatment by a known photoxic agent, 8-methoxypsoralen (8-MOP) or the vehicle (methanol) using the skin of hairless mice, miniature pigs, and man. None of the FWAs was phototoxic. Photocarcinogenesis testing involved pretreating hairless mouse skin with FWAs, 8-MOP, or methanol only before each daily exposure to simulated solar ultraviolet light. In terms of tumor yield and tumor development time, photocarcinogenesis was enhanced by 8-MOP, but not by FWAs.